Telephone-transmitter.



F. R. MGBERTY.

. TELEPHONE TRANSMITTER.

APPLIOATION FILED MAR. 1, 1911.

Patented July 7, 1914.

To all whom it may concern:

ultra sra rns a rn r oruuon.

FRANK R. MCBERTY, OF NEW ROCHELLE, NEW YORK, ASSIGNOR TO WESTERNELECTRIC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF ILLINOIS.

TELEPHONE-TRANSMITTER.

Be it known that I, FRANK R. MoBnRrY,

citizen of the United States, residing at New Rochelle, in the county ofVVestchester and State of New York, have invented a certain new anduseful Improvement in Telephone-Transmltters, of which the fol-Specification of Letters Patent.

Application filed March 1, 1911.

lowing is a full, clear, concise, and exactdescription.

This invention relates to telephone transmitters and its object is toimprove the transmitting qualities of such instruments:

safely withstand. The current manifests itself by heat generated in thecarbon granules and in the electrodes, resulting when the current is toostrong, in what is known as burning. The greatest amount of heat isretained in the granules at the central part of the carbon chamber.

This invention provides improved means for rapidly dissipating the heatgenerated within the carbon chamber, thereby permitting a heavy currentto be used, resulting in very loud and clear transmission withoutburning.?

In accordance with the invention there is provided a comparatively largeblock of good heat conducting material surrounding the carbon chamber.Preferably this block forms the side walls of the chamber and is indirect contact with the carbon granules.

The invention furthermore provides means, preferably in the form ofspurs extending from the surrounding mass of conducting material topoints Within and near the central part of the carbon chamber. Theseprojections may be formed integrally with the surrounding and aregenerally of conical formation.

The invention will be more fully understood by reference to theaccompanying drawing, wherein- Figure 1 is a rear elevation, with theeasing removed, of a telephone transmitter embodying the invention; Fig.2 is a side elevation thereof in section along the line 2-2 of Fig. 1,except that the transmitter elements within the casing are shown in fulllines; Fig. 3 is an enlarged detail front view and Fig. 4 an enlargeddetail sectional View of the transmitter.

In the drawing the transmitter elements Patented July 7, 1914.

Serial N0. 611,631.

' are shown inelosed within a casing 1 and a' face plate 2 to which isattached the usual mouth-piece 3. A diaphragm is supported upon the faceplate and insulated therefrom by a rubber band 5 stretched on its edge,the diaphragm being held in place by a ring 6 which bears against itsedge by pressure'of screws 7 engaging arms 8 of the ring 6 and holestapped in the face plate. Adjustably attached to the central part of thediaphragm by means of a stem 11 and nuts 12 is a front electrode 9 facedwith aplate 10of carbon. The carbon plate 10forms the front Wall of achamber 13, for containing the current carrying carbon granules, therear Wall of the chamber being formed by a second carbon plate orelectrode 14 mounted upon a metallic plate 15 having a screw threaded"stem 16. This back electrode 14 is sunk in a depression of a large metalblock 17 which is centrally tapped to receive the stem 16.

Surrounding the carbon chamber and forming the side walls thereof is alarge metal block 18. The blocks 17 and 18 are of' large mass and ofgood heat conductin material, such as brass or copper, in or or to carryaway from the granules in the carbon chamber the heat developed thereinby the electric current. In order to prevent short paths for the currentfrom one electrode through the block 18 to the other electrode, circularstrips or bands 19 of insulating material such as paper or mica coverthose portions of the inner walls of the block 18 which lie directlyadjacent to the electrodes. However, the mid dle portion of the walls ofthis chamber are left bare thus insuring direct contact between thecarbon granules and the mass of the heat conducting block llxtondinginwardly from the block 18 toward the central portion of the carbonchamber are a plurality of prongs or spurs 26 of metal, generallyconical in shape but flatten ed on either side to avoid close proximitylo the carbon electrodes. These prongs lying in direct contact with thehottest p0rtion of the carbon chmnber and leading directly to the largemass of metal surrounding the carbon chamber provide good heatconducting paths away from the central portion of the mass of carbonwithin the chamber, and also to a certain extent prevent the frontelectrode from being overheated.

The block 17 is secured to the block 18 by screws 20, 20- but insulatedtherefrom by bushings surrounding the screwsand by a mica sheet 21. I

In order to support the working parts of the transmitter in the casing aplate or bridge piece 22 is held to the face plate by flat headed screws23, 23 and adjusting screws 24. The piece 22 embraces the block '18 andis threaded internally at 25 to engage external threads on the block.The

usual mica diaphragm 27 for the front electrode is clamped to the block18 by the screw threaded ring 28 and serves in the usual way to closethe carbon chamber while permitting free vibration of the frontelectrode. Suitable terminals 29, one for the front electrode and theother for the back electrode are mounted upon insulating blocks 30, 30fastened to the bridge piece 22.

I claim:

1. In a telephone transmitter the combination with the electrodesforming the front and rear walls of a chamber and current conhavingprongs extending to the interior of said chamber.

2. In a telephone transmitter the combination with the electrodesforming the front and rear Walls of a chamber and current conductinggranules in said chamber, of a relatively large block of good heatconducting material surrounding said chamber and forming the side Walls.thereof, and a lurality of heat conducting prongs general y conical inshape extending from the middle pol,- tion of said chamber to saidblock.

In Witness whereof, I, hereunto subscribe my name this 28th day ofFebruary A. D

FRANK R. MCBERTY. Witnesses g f IRVING MACDONALD, MORGAN WABHBURN, Jr.

